Bulwark

The best offense is a great defense. The Bulwark embodies this by making use of shields and armor to deliver deadly blows.

Shieldmaster

Starting at 3rd level, you learn to use your shield as an offensive tool. Whilst in your hand, your shield counts as a martial melee weapon, and it deals 1d6 plus your Constitution modifier bludgeoning damage on a hit. You can use Strength or Constitution for the attack roll with attacks with your Shield. After you hit a creature with a melee weapon attack, you can use your bonus action to make a weapon attack against that creature, using your shield. You also get a +1 bonus to AC while wielding a shield and no other weapon. You can still wear another shield and benefit from this property.

Additionally, you gain a number of Armor dice equal to your level in this class, which are d4.You can use your armor dice to use the following effects:
• As a bonus action, you can spend an armor die to bolster your resolve, granting yourself a bonus to your armor class equal to the rolled result until the beginning of your next turn.
• If a creature leaving your range would provoke an opportunity attack from you, you can spend an armor die to make an opportunity attack against that creature. If you hit, subtract the rolled result to that creature's movement for this turn.
• If a creature makes a melee weapon attack against you and misses, you can use your reaction to expend an armor die and make a melee weapon attack against that creature, using your shield, adding the rolled result to the attack roll.

You regain all of your armor die after a short or long rest, and the quality of your armor dice increase as you gain levels in this class, increasing to d6 at 5th level, d8 at 10th level, d10 at 15th level, and d12 at 20th level.

Shield Bash

Starting at 7th level, your melee attacks using a shield now do 1d8 bludgeoning damage, and if your shield is a magic item, your shield attacks count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

In addition, once per turn after you hit a creature with a melee weapon attack using your shield, you can expend an Armor die to attempt a stunning strike as a bonus action. The target must succeed on a Constitution saving throw or be stunned until the end of your next turn.

Indomitable Defense

At 10th level, when you use your Second Wind or Action Surge feature, you gain temporary hit points equal to your AC.

Additionally, if an ally within 5 feet of you is hit by an attack, you can use your reaction to expend one of your armor die, granting your ally a bonus to their AC equal to the rolled number for the turn, potentially causing the attack to miss.

Superior Defense

Starting at 15th level, while you are wearing medium or heavy armor, you can add your Constitution modifier to your armor class (minimum of one).

Additionally, damage rolls with your shield now deal 1d10 bludgeoning damage, and you have advantage on opportunity attacks against enemies.

Impenetrable Shield

At 18th level, you become the living embodiment of stalwartness. While you are wearing heavy armor, you gain resistance to piercing, slashing and bludgeoning damage from nonmagical sources.

Additionally, whenever a creature makes an attack against you and hits, you can use your reaction to expend one of your Armor die to reduce the damage dealt to you equal to the rolled number.